Adjustable actuating arm



July 3, 1962 w. F. DEHN 3,041,888

ADJUSTABLE ACTUATING ARM Filed May 2, 1960 INVENTOR WILLIAM F'. DEHN ATTORNEY llnited rates atent 3&41583 Patented July 3, 1962 3,941,888 ADJUST BLE ACTUATENG AEM William F. Debra, Wauwatosa, Wis, assignor to Allen- Eradley (Iompany, Milwaukee, Win, a corporation of liiseonsin Filed May 2, 1560, Ser. No. 26,010 7 Claims. (El. 74-559) This invention relates to adjustable actuating arms for use with devices having rotatable control shafts; and it more particularly resides in an angularly adjustable actuating arm having a block portion adapted to be securely mounted on a control shaft and disposed in rough angular adjustment relative thereto and an actuating arm portion pivotally mounted intermediate its ends on said block and having an inner end adapted for engagement with an adjusting shaft, said adjusting shaft serving to pivotally actuate the arm portion to a position of fine angular adjustment relative to the block and the control shaft.

Although this invention has been designed primarily for use with electrical limit switches, it will be apparent from the description to follow that it is readily adaptable for use with a number of devices. Specifically, the invention herein may find use in connection with any device having a rotatable control shaft operable in response to an actuating arm radially extending therefrom.

Actuating arms for use with devices of the foregoing class have, heretofore, generally depended for their angular adjustment only upon the means, usually threaded, used to clamp the arm or arm assembly to the control shaft. Since the control shaft of such a device must itself be freely rotatable, securing the actuating arm thereon require the operator to hold the shaft in place while tightening the clamping means. Due to the difficulty involved in such a procedure, the resulting angular adjustment is generally rough at best.

Accordingly, it is the primary object of this invention to provide an angularly adjustable actuating arm which may be first securely mounted to a control shaft in rough angular adjustment, and then moved to and held in a position of fine adjustment without disturbing its mounting on the shaft, and which arm may further include means to eliminate backlash between relatively adjustable operating components.

it is a further object of this invention to provide such.

an actuating arm which is easily reversible face-for-face, and which may include a variety of sensing devices for operation thereof.

It is a still further object of this invention to provide such an actuatim arm of sturdy and effective, but inexpensive, construction.

The foregoing are merely illustrative and further objects and advantages will become apparent from the description to follow. In the description, reference is made to the accompanying drawing, forming a part hereof, in which there is shown by way of illustration and not of limitation a preferred embodiment of the invention.

in the drawing:

FIG. 1 is a perspective view of an electrical limit switch on which is mounted an actuating arm embodying theinvention;

FIG. 2 is a front view in elevation, with parts broken away and in section, of the actuating arm mounted as shown in FIG. 1, and in particular, the section taken along lines 2-2 of FlG. 3;

FIG. 3 is a side view in elevation, with parts broken away and in section, taken along the plane of lines 3-3 of FIG. 2.

Referring now to FIG. 1, there is illustrated an electrical limit switch 1 having a body portion 2 and an operating head 3. On the front face t of the operating head securing the block 3 is mounted, by means of spaced assembly screws 5, a bearing 6. Journalled in the bearing 6 and projecting outwardly of the head 3 is a rotatable control shaft 7 having a screw head slot 8. Rotation of the shaft 7 serves to operate in any desired manner the internal parts of the switch 1. Since, however, the internal construction of the switch 1 is of no consequence to the invention herein described, which invention is usable with a number of devices, the details thereof are neither shown nor described herein.

Mounted on the shaft 7 is an actuating arm 9, comprising a block portion 1t and an actuating arm portion 11, the details of which will now be described with particular reference to FlGS. 2 and 3.

The block portion it} of the arm 9, which may be cast of brass or any suitable material or otherwise formed, comprises a pair of spaced upwardly extending bifurcated elements 13 defining therebetween a vertically extending slot 14 having near its lower end and communicating therewith, a transverse cylindrical bore portion 15 of somewhat greater diameter than the width of the slot M. Below the bore portion 15 and in communication therewith is an extension of the slot 14- which forms a relatively shallow transverse trough 16.

Extending forwardly through the block 10 is a cylindrical bore 17 of sufficient size to snugly accommodate therein the shaft 7. Another cylindrical bore 18 trans versely of the bore 17 is arranged to freely slidably receive a set pin :19 having a circular indent portion 20 intermediate its ends and a threaded end portion 21. A nut 22 threadedly engages the end portion 21. The arrangement of bores 17 and 15, the indent portion 20, the set pin 19 and the nut 22 serve as one possible means to mount the block it) on the shaft 7 in a manner which Will now be described. The circular indent portion 29' is placed in register with the opening 17 upon rotation of the pin 19, whereby the block ill may he slid over the shaft 7. The nut 22 is portion 24) of the pin 19 slightly out of register with the bore 17, to thereby securely lock the block Ill against the shaft .7. It will be obvious that the block :10 should be placed on the shaft 7 in a position of rough angular adjustment, and, in order to maintain the block 10 in its proper position relative to the shaft 7 while the nut 22 is being tightened, a screw driver or other tool may be inserted into the screw head slot 8 to restrain the shaft 7 against rotation. Although the foregoing manner of to the shaft has proven quite satisfactory, it forms no part of the invention herein and it should be understood that any other suitable means may be used, it being necessary only that the block be securely mounted to the shaft in a position of rough angular adjustment.

Extending through the bore portion 15 of the block it? is an adjusting shaft, preferably in the form of a threaded worm 23, which may be of slightly smaller diameter than that of the bore portion 15. The worm 23 is provided at one end with an enlarged head 24, preferably of sufiicient size to cover the 'bore portion 15 and the trough i6 and provided with a socket 25 having polygonal sides, said socket being useful for adjustment of the operating shaft or worm 23 in a manner to be hereinafter described. Below the worm 23 and disposed within the trough 16 is a biasing member 26, preferably in the form of a leaf spring, which serves to urge the worm 23 upwardly within the relatively larger bore portion 15. On the end of the worm 2 3 opposite from the head 24 is mounted a circular washer 27 preferably of sufiicient size to cover the bore portion 15 and the trough 16. Adjacent and outwardly of the washer 27 is mounted a spring washer 28 or other resilient means. The worm 23 is preferably spun or riveted over, as at 29, to hold the washers 27 and 28 firmly in place, the spring washer then tightened to force the indent 3 28 serving to hold the worm 23 securely against axial float.

Disposed snugly within the slot 14 is the generally triangular shaped actuating arm portion ll l preferably cast or otherwise formed of beryllium copper or other material of suitable hardness. The arm portion 11 is provided with an aperture 30 which is in register with matching openings 31 and 32 in the bifurcated elements 13. A pivot pin 33, which may be in the form of a threaded set screw, passes through the openings 36, 31 and 32 whereby the arm portion l1 is pivotally mounted on the block 10. The pivot pin 33 is provided with an enlarged head 34 which may be knurled and provided with a socket 35 having polygonal sides. The opening 31, remote from the head 34 of the pin 33, is preferably threaded, whereby tightening of the threaded pivot pin 33 will cause the bifurcated elements 13 to be clamped against the arm portion 11 to hold the same firmly in place. The inner end 36 of the arm portion 30 is arcuate, the center of which are is preferably the pivot pin 33. Formed along the arcuate end 36 are a plurality of teeth 37 in meshing engagement with the worm 23, the inner end 36 of the arm portion 11 thus constituting a Worm gear. The biasing member 26 serves to hold the worm 23 and the teeth 37 in tight engagement and thereby to prevent backlash movement therebetween. Further, the secure engagement afforded by the biasing member 26 serves to compensate for the relative bluntness of the teeth 37 which may result when the arm portion 11 is formed by casting. In addition, it will be apparent that the teeth 37, when cast under presently known die-casting techniques, can only be cast straight, and not in the preferred helix. The biasing member 26 will also act to compensate for this condition.

On the outer end 38' of the arm portion Ill is mounted a rotatable contact roller 39, which may be formed of a plastic material, such as nylon or Teflon, as shown herein, or of metal, such as steel, and may further take the form of a ball or roller bearing. Alternatively, any suitable sensing means may be used in place of the contact roller 39. The roller 39 is shown in the drawing herein as being on the outer side of the arm portion 11 with respect to the switch 1. The arm portion 11 or the block may easily, however, be reversed, face-for-face, whereby the roller 39 will be mounted inwardly thereof.

In operation, and after the block 10 has been secured to the shaft 7 in a position of rough angular adjustment as previously described, the pivot pin 33 is loosened, should it be in the form of a set screw as shown herein. An Allen head wrench or other suitable tool may then be inserted into the socket 25, whereby the worm 23 may then be rotated. As the worm 213 is rotated, its engagement with the end, or worm gear, 36 of the arm portion 11 causes the arm portion 11 to be pivoted about the pivot pin 33, whereby the roller 39 or other sensing device is moved to a position of fine adjustment relative to the actuating arm 9 and its supporting shaft 7. When the desired position is reached, the pivot pin 33 may again be tightened to help maintain the arm portion 11 in position, although the firm engagement of the parts due to the biasing member 26 will itself serve to hold the arm portion 11in place in most cases. The embodiment shown herein includes an arm portion arranged to pivot 7 /2 degrees from vertical in either direction, but it will be obvious that greater or lesser degrees of adjustment may be provided within the scope of the invention.

It can thus be seen that the angularly adjustable actuating arm of the invention herein comprises both a block portion mountable on a control shaft in rough angular adjustment relative thereto, and an actuating arm portion which is pivotal with respect to the block in the manner described, whereby the arm portion may be moved to a position of fine adjustment, the assembly preferably being held against backlash movement by bias means constituting biasing member 26.

Although a preferred embodiment of the invention has been shown herein, however, it is desired that it be understood that the invention is not to be limited to the specific form and arrangement of parts shown except insofar as such limitations appear in the following claims.

I claim:

1. The combination of claim 6, wherein the bifurcated parts are resilient and there is provided a threaded set screw which serves to pivotaily mount the arm portion on the block and threadedly engages one of the bifurcated parts, whereby tightening of the set screw causes the bifurcated parts to clampingly engage the arm portion therebeti een in adjusted position.

2. In a device having a rotatable'control shaft, an actuating arm for said shaft comprising: a block mounted on and pivotable about the control shaft, said block having a body portion mounted on the control shaft and a bifurcated extension radially spaced from the control shaft and comprising spaced bifurcated parts defining a slot therebetween that is transverse to the axis of the control shaft, the opposed internal surfaces of said slot defining an open-ended portion, an intermediate cylindrical bore portion and a closed end portion at the end of the slot nearest the control shaft, the openended portion being of a width less than the diameter of said bore portion; means to secure the body portion to the control shaft in a position of rough angular adjustment; pivot support means arranged transversely through the open-ended portion of said slot; a rotatable threaded adjusting shaft disposed within said cylindrical bore portion, said adjusting shaft being of a diameter less than the diameter of said cylindrical bore portion and greater than the width of said open-ended slot portion; an arm portion supported intermediate its ends by said pivot support means and disposed within said open-ended portion, said arm portion having an arcuate inner end defining a plurality of teeth engageable with said threaded adjusting shaft and an outer end that is adapted to receive a sensing device and extending away from the control shaft whereby rotation of the adjusting shaft causes the arm portion to be pivoted in a plane parallel to the plane of pivotal movement of the block about the control shaft thereby moving the outer end of the arm portion to a position of fine angular adjustment with respect to the control shaft; and resilient means disposed within the closed end portion of said slot and holding the adjusting shaft in tight threading arrangement with said arm portion.

3. In a device having a cylindrical rotatable control shaft, an actuating arm for said shaft comprising: a block having a body portion with a cylindrical opening through which the control shaft is received, said body portion being pivotable about the control shaft, and a radially extending bifurcated portion comprising spaced resilient bifurcated .parts defining a slot therebetween that is transverse to the axis of the control shaft, the opposed internal surfaces of said slot defining an openended portion, an intermediate cylindrical bore portion and a closed end portion that is nearest to the control shaft, the open-ended portion being of a width less than the diameter of said bore portion; means to secure the body portion to the control shaft in a position of rough angular adjustment; threaded pivot support means arranged transversely of the open-ended portion of said slot and threadedly engaged with one of the bifurcated parts whereby tightening of the pivot support means causes the bifurcated parts to be moved toward one another; a rotatable threaded adjusting shaft disposed within said cylindrical bore portion and having end portions extending outwardly of said block, said adjusting shaft being of a diameter less than the diameter of said cylindrical bore portion and greater than the width of said open-ended slot portion; resilient means mounted on the extending end portions of said adjusting shaft to restrain said adjusting shaft against axial float; an actuating arm 7 portion supported intermediate its ends by said pivot support means and disposed within said open-ended portion, said arm portion having an arcuate inner end defining a plurality of teeth engageable with said threaded adjusting shaft and an outer end bearing a sensing device and extending away from the control shaft whereby rotation of the adjusting shaft causes the arm portion to be pivoted in a plane parallel to the plane of pivotal movement of the body portion about the control shaft thereby moving the outer end of the arm portion to a position of fine angular adjustment relative to the control shaft; and resilient means disposed within the closed end portion of said slot and holding the adjusting shaft in tight threading engagement with said arm portion.

4. In an actuating lever arm for a device having a rotatable control shaft, the combination comprising: a block mounted on and pivotable about said control shaft and having a radial extension containing a bore extending from one side to the other and a trough with a bottom and two sides that is directly beneath the bore and opens into the bore along its length and an open-ended slot above and communicating with the bore; means to secure the block to the control shaft in a selected pivoted position; an actuating arm portion pivotally mounted intermediate its ends in the slot with an arcuate, toothed inner end extending into the bore and an outer end extending away from the control shaft; a threaded adjusting shaft extending through the bore and overlaying the trough which is in engagement with the teeth of the actuating arm portion, said adjusting shaft having a head at one end bearing against a side of the block and closing off one end of the trough; resilient means at the opposite end of the adjusting shaft urging the adjusting shaft axially to bring up the head end tight against the block and also closing over the other end of the trough; and a leaf spring held captive in said trough by the adjusting shaft, the head of the adjusting shaft and the resilient means, said leaf spring bearing against the bottom of the trough and against the adjusting shaft to retain the adjusting shaft tight against the toothed arcuate end of the actuating arm portion.

5. In a device having a rotatable control shaft, an actuating arm for said shaft comprising: a block mounted on and pivotable about the control shaft and having a portion extending radially therefrom, said radially extending portion having an open-ended slot therein that extends transversely to the axis of the control shaft with its open end facing radially outwardly from the control shaft; means to secure the block tightly to the control shaft in a selected position of rough angular adjustment with respect to the control shaft; a threaded adjusting shaft rotatably mounted in the slot; an arm portion pivotally mounted intermediate its ends on the radially extending portion of the block, said arm portion having an outer sensing end extending away from the control shaft and an arcuate inner end extending toward the control shaft with teeth thereon, said teeth being in meshing engagement with the adjusting shaft whereby rotation of the adjusting shaft causes the arm portion to be pivoted with respect to the block to move the outer end of the arm portion to a position of fine angular adjustment with respect to the control shaft; and resilient means disposed within the slot and acting between the block and the adjusting shaft to hold the adjusting shaft tightly against the teeth of the arm portion.

6. In a device having a rotatable control shaft, an actuating arm for said shaft comprising: a block having a body portion mounted on and pivotable about the control shaft and a bifurcated portion radially spaced from the control shaft and comprising spaced bifurcated parts defining a slot therebetween; means to clamp the body portion of the block securely to the control shaft in a selected position of rough angular adjustment with respect to the control shaft; a rotatable threaded adjusting shaft disposed within the slot; an arm portion disposed within the slot and pivotally mounted intermediate its ends on the bifurcated portion of the block outwardly from the adjusting shaft, said arm portion having an outer end extending away from the control shaft that is adapted to receive a sensing device and an arcuate inner end extending toward the control shaft with teeth thereon that are in meshing engagement with the adjusting shaft whereby rotation of the adjusting shaft causes the arm portion to be pivoted to move the outer end thereof to a position of fine angular adjustment with respect to the control shaft; and resilient means disposed within the slot and acting between the body portion of the block and the adjusting shaft to hold the adjusting shaft in a tight engagement with the teeth of the arm portion.

7. The actuating arm of claim 3 wherein the teeth of the arm portion are relatively blunt and are substantially perpendicular to the axis of the adjusting shaft.

References Cited in the file of this patent UNITED STATES PATENTS 65,114 Perkins May 28, 1867 284,703 Zsechech Sept. 11, 1883 642,710 Palmer Feb. 6, 1900 954,515 -IIenry Apr. 12, 1910 1,724,292 Lawrence Aug. 13, 1929 1,812,492 Lee et a1. June 30, 1931 1,909,182 Lavagan May 16, 1933 2,313,768 Putt Mar. 16, 1943 2,428,832 Charbonneau Oct. 14, 1947 2,466,077 Biggs Apr. 5, 1949 2,631,472 MacDougall Mar. 17, 1953 2,650,681 Shively Sept. 1, 1953 2,836,081 Dehn May 27, 1958 2,960,886 Cunningham Nov. 22, 1960 FOREIGN PATENTS 899,741 Germany Dec. 14, 1953 OTHER REFERENCES 14 Adjusting Devices Design Roundup (2 pages) in Product Engineering Design Issue, -vol. 29, No. 44. October 27, 1958.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,041,888 July 3, 1962 William F. Dehn It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 46, for

arrangement" column 5, line 14,

read engagement strike out "lever".

Signed and sealed this 27th day of November 1962.- t v (SEAL) Attest:

we! DAVID LADD Atteating Officer Commissioner of Patents 

